The clipboard is a data transfer feature of the "MICROSOFT" WINDOWS, version 3.1, operating system sold by Microsoft Corporation of Redmond, Wash. The clipboard is used to transfer data between applications or within a single application. The clipboard includes a set of functions and messages that enable applications to transfer data via the clipboard. The clipboard may be viewed as a common area for storing data handles (i.e., unique identifiers for data objects) to which applications can exchange formatted data. The "MICROSOFT" WINDOWS, version 3.1, operating system enumerates a fixed number of clipboard formats. For example, the CF.sub.-- BITMAP clipboard format is used for transferring bitmaps, and the CF.sub.-- TEXT clipboard format is used for transferring arrays of text characters. The clipboard may simultaneously hold the same data in different clipboard formats.
Users of applications use the clipboard by calling clipboard commands, such as "cut", "copy" or "paste". The copy clipboard command copies a selected portion of data in a clipboard format to the clipboard by copying a handle to the data object that holds the selected portion of data in a clipboard format to the clipboard. The selected portion of data is not removed from the source from which it originated. The cut clipboard command is similar to the copy command in that it copies a selected portion of data to the clipboard, but the cut clipboard command differs from the copy clipboard command in that it removes the selected portion of data from the source of the data. The paste clipboard command copies data from the clipboard to a destination.
The Microsoft OLE 2.01 protocol, established by Microsoft Corporation, provides a mechanism for facilitating drag and drop operations. This mechanism uses clipboard formats. The data, however, is not passed through the system store that is used for cut and copy operations; instead, the transfer is directed from source to destination.
Although the clipboard is useful, the formatting constraints are too limiting for many applications. In particular, the number of clipboard formats provided by the system is too few, and the available formats are too limited.